Final answer:
The wet hand will be cooler than the dry hand because of the evaporation cooling effect, where heat is absorbed from the skin during water's phase change, despite both hands actually being at the same temperature when measured scientifically.
Step-by-step explanation:
The difference between a wet hand and a dry hand after pouring warm water on one is essentially about heat transfer and the sensation of temperature. Option A, 'The wet hand will be cooler than the dry hand,' is correct because when water on the wet hand evaporates, it absorbs heat from the skin, thereby cooling it down. This is akin to the concept of evaporation cooling, which is also why we feel cooler when sweat evaporates from our skin on hot days. To understand this better, let's consider a simple experiment. If you were to hold your right hand in hot water and your left hand in cold water for about 3 minutes, and then place both hands in room-temperature water, the right hand would perceive this water to be cool, while the left hand would feel it to be relatively warm. This demonstrates that the sensation of hotness or coolness is relative and dependent on previous conditions. Moreover, despite the different sensations, if thermometers were used, both hands in the room-temperature water would show the same temperature, highlighting the scientific measurement of temperature in contrast to human perception.